This invention relates generally to radiography and, more particularly, to radiographic systems for producing tomographic, i.e., cross-sectional radiographic images.
Radiographic techniques using either x-rays or gamma rays are, of course, widely used in medicine. In general, most radiographic techniques depend upon the principle that radiation directed at some portion of a patient's anatomy will be blocked or attenuated to some degree depending upon the thickness, density and other characteristics of the irradiated substances. In conventional radiographic processes, x-rays are transmitted through a patient to a photographic film, where variations in thickness and density characteristics are recorded.
More recently, there has been much interest and development in the field of tomography, sometimes known as sectional radiography, which is the technique of making radiographs of plane sections of a body or object. In one tomographic technique, a pencil beam of x-rays is scanned through the patient along the plane to be examined, and a detector is utilized to monitor the intensity of the beam after it has traversed the patient. The x-ray source and detector assembly are slowly rotated about an axis substantially perpendicular to the plane of interest, and more radiographic data are collected at each incremental angular position. The data can then be correlated by computer, to generate a tomograpic image of the entire cross-section. Although this technique is highly effective, it requires relatively complex equipment to obtain and analyze the radiographic data, and to display the resultant tomographic images.
Accordingly, there is still a need in the field of tomography for a simplified technique for producing tomographic images, and it is to this end that the present invention is directed.